Research in the coming year will focus on the role of the basal ganglia in motor behavior. Single unit recording will be done in the putamen, globus pallidus and subthalamic nucleus of monkeys trained to maintain joint position during the application of various loads. In addition to these isometric studies, the activity of basal ganglia neurons will be examined during step movements executed under assisting and opposing load conditions. The characteristic response of each nucleus will be determined as the basis for the characteristic response of the basal ganglia as an intact sytem.